import intsets, unicode, sequtils

proc isIsogram*(input:string):bool = 
  var seen = initIntSet()
  
  not anyIt(toSeq(input.toLower.runes),
     isAlpha(it) and seen.containsOrIncl(ord it))

  # for c in input.toUpper.runes:
  #   if isAlpha(c) and set.containsOrIncl(ord c):
  #     return false
  # return true